Apparatus for upward casting

ABSTRACT

Profiled metal products are continuously cast by maintaining a nozzle having an upper cooling zone immersed into a melt to receive and cool the melt. The nozzle is immersed so deep into the melt that the point of solidification of the received melt is below the surface level of the outside melt and the solidified smelt is then pulled upwards while being further cooled.

United States Patent 1 Lohikoski et al.

[11] 3,746,077 1451 July 17, 1973 1 APPARATUS FOR UPWARD CASTING [75] Inventors: Timo J. J. Lohikoski; Mauri V.

Rantanen; Heimo H. Hocksell, all of Pori, Finland [73] Assignee: Outokumpu 0y,Outokumpu,

Finland 221 Filed: May 12, 1971 21 Appl. No.: 142,532

[30] Foreign Application Priority Data May 19, 1970 Finland 1403 [52] US. Cl. 164/281, 164/283 [51] Int. Cl B22d 11/10 [58] Field of Search 164/84, 85, 281, 164/283 [56] References Cited UNITED STATES PATENTS 1,727,191 9/1929 Baily 164/283 2,405,355 8/1946 Harrison 164/283 X 2,553,921 5/1951 Jordan 164/85 X 2,667,673 2/1954 Harrison 164/283 X 3,022,552 2/1962 Tessmann 164/283 X 3,410,333 11/1968 Woodburn, Jr 164/85 X FOREIGN PATENTS OR APPLICATIONS 903,137 2/1954 Germany 164/281 Primary ExaminerR. Spencer Annear AttorneyLorimer P. Brooks et al.

[57] ABSTRACT Profiled metal products are continuously cast by maintaining a nozzle having an upper cooling zone immersed into a melt to receive and cool the melt. The nozzle is immersed so deep into the melt that the point of solidification of the received melt is below the surface level of the outside melt and the solidified smelt is then pulled upwards while being further cooled.

5 Claims, 1 Drawing Figure 1 APPARATUS FOR UPWARD CASTING BACKGROUND OF THE INVENTION 1. Field of the Invention The invention relates to the field of upwards casting of profiled products from a metal melt.

2. Description of the Prior Art A continuous casting process for the casting of pipes by using a graphite nozzle open at both ends and a conical core centered inside it is known from, for example, U.S. Pat. Nos. 2,466,612 and 3,375,863. In this process the graphite nozzle is attached to the bottom of the melt container with its longitudinal axis in a vertical position so that the nozzle end to which the core has been attached reaches into the melt container and the other end is inside a water-cooled chill mold. When melt is drawn through the nozzle, it solidifies and is a solid pipe on emerging from the nozzle.

In this way it is possible to cast high quality pipes with walls that are evenly thick on all sides. A disadvantage of this process is that, when the nozzle is changed, at least the part of the furnace to which the nozzle has been attached must be freed from the melt, that is, the furnace must be emptied or tilted so that the area concerned is left above the melt surface. This disadvantage is especially noticeable when several nozzles have been attached to the same furnace. Their ages of duration are not the same, but since they all must be changed at the same time, some of them have to be out of use for some time, and some of them will be removed from use too soon. In addition, it is always possible in the process that melt will discharge freely out through the nozzle, in which case the employees and equipment are easily harmed.

Another well-known method for the casting of pipes is a horizontal variant of the above. In this process the nozzle is attached to the wall of the melt container, the longitudinal axis of the nozzle being in a horizontal position. This process has the same disadvantages as the vertical one, but in addition the resulting pipe will easily be eccentric. Gravity makes the cold metal sink to the lower part of the nozzle with the consequence that the solidifying front becomes oblique. Because the lower part solidifies first, it has, owing to the conical shape of the core, thinner walls than the upper part which solidifies later.

An upward casting process for pipes was introduced by J.F. Jordan in the U.S. Pat. No. 2,553,921. In this process a water-cooled metal nozzle, protected by a fireproof lining, is immersed into the melt from above and the solidifying bar is drawn upward at such a fast speed that the center still remains in a melted state above the free surface of the melt container. Since the melt does not rise above the surface a pipe is obtained, and the inner surface of the pipe is determined by the melted area inside the pipe. It is mentioned in the description of the process that the gases which are contained in the melt and which are freed during the solidification phase can be removed through the free smelt surface inside the pipe.

This process has some weaknesses and it has hardly ever been used on an industrial scale. Firstly, no metal alloy is yet available which could be used for the nozzle in casting metals which melt at high temperatures, when one end of the nozzle reaches into the smelt. Secondly, it is very difficult to obtain such even cooling conditions that the quality of the inner surface of the pipe would be good enough, since it is determined by the thickness of the layer solidified at a certain point. Thirdly, there is a structural weakness in the device; it is almost impossible to make the seam between the metal nozzle and the ceramic insulator tight enough to prevent metal melt from squeezing into it, especially as these two materials expand with heat in different ways. When melt squeezes into a crack such as this, it solidifies there under the influence of the cold nozzle wall and causes cracks and even breaks when it sticks to the cast product.

Obviously prejudices against the harmful effect of gases have been the reason why the following suggestion for a continuous upward casting process for pipes was not made until in copending U.S. application Ser. No. 95,038, assigned to the same assignee as this application and filed Dec. 4, 1970, hereby incorporated by reference.

SUMMARY OF THE INVENTION According to the invention the nozzle inlet is maintained at such a depth below the melt surface that also the solidification front of the received smelt is below the level of the melt outside the nozzle.

The advantages of the invention will appear from the following Description of the Preferred Embodiment.

BRIEF DESCRIPTION OF THE DRAWING The FIGURE shows an elevational section of an especially preferred embodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT With reference to the FIGURE, a core 8 has been attached inside the nozzle and centered with the help of a guiding surface 10. The material of these parts is usually solid graphite, but it can also be some other material, for example, sintered alloy of metal and metal oxide. Passages 12 run through the base of the core 8. Melt is conducted through the passages 12 into the solidification area between the nozzle 7 and the core 8. The nozzle 7 has been attached to the metal chill mold 2 by threading shown at 9 so that it conducts heat well. Cooling water runs to the chill mold 2 through pipe A. The water is forced to run to the lower end of the chill mold along the space between the outer pipe 4 and the intermediate pipe 3 and then up along the space between the intermediate pipe 3 and the inner pipe 2 and out through pipe B.

The lower end of the chill mold 2 is protected by a fireproof lining 6 which is attached so tightly to the lower end of the nozzle 7 by, for example, a conical surface ll and a nut 5, that melt will not get into contact with the metal chill mold' 2.

The basis of the operation of the device is that the chill mold is immersed from above so deep into the melt that teh solidifying front 13 is below the free surface 14 of the melt. The solidified pipe generally indicated by the reference numeral 1, is drawn upward by a drawing apparatus situated above the device and not shown in the figure. The continuation of the inner pipe 2 above the upper surface of the nozzle 7 works as an after-cooler of the already solidified pipe.

The inner surface of the forming pipe is determined by the diameter of the core at the solidifying front 13. By changing the conditions so that the solidifying front 13 is made to move, it is possible to affect the inner diameter to some extent even during the casting.

The device presently described differs from the one described in the U.S. patent application Ser. No. 95,038 in that it is not necessary to use differences of pressure in relation to the open air. In the case of casting pipes the use of underpressure would cause great technological difficulties since the entire cast pipe ought to be in the same pressure. The cutting of the product should also take place without disturbing the underpressure prevailing inside the pipe. The construction of an underpressure chamber is particularly difficult when the purpose is to cast very long pipes, for example, m long.

It has been noted that with a simple construction several pipes can be cast simultaneously from the sme melt container by a device according to the invention so that none of the nozzles disturb the operation of the others. The pipes obtained are accurately dimensioned, and because of the casting direction the variation of the wall thickness is small. Gases have not been notices to cause disturbances. 7

Example: Pipe, the dimensions of which were 60/46 mm, was cast by a device according to the invention from the alloy CuNilOFe according to DIN standard 17664. The casting rate was 25 cm/min and the flowing rate of the cooling water 20 11min. The structure of the obtained pipe was solid and its eccentricity was less than i 1 percent of the wall thickenss.

A device according to the invention can be used for the production of casts of unlimited length. The diameter of the cast is determined by the nozzle 7 and the core 8. The advantages of the device are most obvious in casting pipes.

ln addition to the continuous casting of hollow form parts, a device according to the invention can be used, by removing the core, for the continuous casting of bars and different profiles, plates, etc.

What is claimed is:

1. An improved apparatus for casting profiled products continuously upwards from a melt having: a support above the melt; a vertical cooler attached to the support, said cooler comprising a plurality of concentric pipes defining a passage therebetween having an inlet and an outlet for coolant medium; and means for pulling solidified product upward through the cooler, the improvement comprising a nozzle coaxially attached to and partially surrounded by the lower end of the cooler to cool the upper portion of the nozzle and a fireproof lining encompassing the nozzle and at least the lower part of the cooler.

2. The apparatus of claim 1, in which the nozzle has an outer surface which expands conically toward the lower end of the nozzle and the lower end of the lining has an inner surface mating with and resting on said conical outer nozzle surface, the upper end of the lining being fixed to the cooler by means of a nut.

3. The apparatus of claim 1 in which the lower end of the nozzle has an internal guiding surface for centering a core inside the nozzle and there is an annular space between the nozzle and the core, a base of the core having a plurality of passageways providing inlets for the melt to the annular space.

4. A device for immersion into molten metal for upward casting of elongate elements from the molten metal, including a nozzle, a cooler surrounding only an upper part of the nozzle to provide a cooling zone within the upper part of the nozzle for continuously cooling molten metal within the nozzle to form a solidified product below the surface level of molten metal into which the device is immersed, and a fireproof sheath surrounding the nozzle and also surrounding at least a lower part of said cooler.

5. The device of claim 4 wherein an uncooled lower portion of the nozzle having a length at least one quarter of the total axial length of the nozzle extends below the cooler. 

1. An improved apparatus for casting profiled products continuously upwards from a melt having: a support above the melt; a vertical cooler attached to the support, said cooler comprising a plurality of concentric pipes defining a passage therebetween having an inlet and an outlet for coolant medium; and means for pulling solidified product upward through the cooler, the improvement comprising a nozzle coaxially attached to and partially surrounded by the lower end of the cooler to cool the upper portion of the nozzle and a fireproof lining encompassing the nozzle and at least the lower part of the cooler.
 2. The apparatus of claim 1, in which the nozzle has an outer surface which expands conically toward the lower end of the nozzle and the lower end of the lining has an inner surface mating with and resting on said conical outer nozzle surface, the upper end of the lining being fixed to the cooler by means of a nut.
 3. The apparatus of claim 1, in which the lower end of the nozzle has an internal guiding surface for centering a core inside the nozzle and there is an annular space between the nozzle and the core, a base of the core having a plurality of passageways providing inlets for the melt to the annular space.
 4. A device for immersion into molten metal for upward casting of elongate elements from the molten metal, including a nozzle, a cooler surrounding only an upper part of the nozzle to provide a cooling zone within the upper part of the nozzle for continuously cooling molten metal within the nozzle to form a solidified product below the surface level of molten metal into which the device is immersed, and a fireproof sheath surrounding the nozzle and also surrounding at least a lower part of said cooler.
 5. The device of claim 4 wherein an uncooled lower portion of the nozzle having a length at least one quarter of the total axial length of the nozzle extends below the cooler. 